formatting – Exapanding and Sympifying expression when using typesetting format


I’m starting to learn Mathematica, and in the book that I’m reading the author presented the commands “Simplify” and “Expand”. Now, the example in the book was the following:

Simplify((x^3 - y^3)/(x - y))

Now, this commend works, and outputs $x^2 + x y + y^2$. The problem is, if I use the
typesetting notation, the function doesn’t actually work:

Simplify($frac{x^3 – y^3}{x-y}$)

The above command outputs $frac{x^3 – y^3}{x-y}$, instead of the simplified form. The same happens for the command “Expand”.

Is there a way around this? As asked in the comment, here is the output of

Simplify($frac{x^3 – y^3}{x-y}$)FullForm

!(
TagBox(
StyleBox(
RowBox({"Times", "(", 
RowBox({
RowBox({"Power", "(", 
RowBox({
RowBox({"Plus", "(", 
RowBox({"x", ",", 
RowBox({"Times", "(", 
RowBox({
RowBox({"-", "1"}), ",", "y"}), ")"})}), ")"}), ",", 
RowBox({"-", "1"})}), ")"}), ",", 
RowBox({"Plus", "(", 
RowBox({"x\.b3", ",", 
RowBox({"Times", "(", 
RowBox({
RowBox({"-", "1"}), ",", "y\.b3"}), ")"})}), ")"})}), ")"}),
ShowSpecialCharacters->False,
ShowStringCharacters->True,
NumberMarks->True),
FullForm))